Articular surface of the medial proximal tibia is aligned parallel to the ground in three-dimensional space under weight-bearing conditions for healthy and osteoarthritic knees. Issue 1 (April 2020) - Mochizuki, T.; Koga, Y.; Mori, T.; Nishino, K.; Tanifuji, O.; Kobayashi, K.; Koga, H.; Omori, G.; Tanabe, Y.; Sakamoto, M.; Endo, N.